Recently, in German Offenlegungsschrift No. 2,165,651 a group of isoindole-1,3-diones which are useful as herbicides was disclosed. The general formula for the isoindole-1,3-diones disclosed in the Offenlegungsschrift is as follows: ##STR2## wherein R may be an aryl, aralkyl or benzyl substituent optionally substituted with 1 to 5 halogen atoms or a hydroxy, nitro, cyano, thiocyanato, carboxy, alkyl or halogenated alkyl, alkoxy, lower alkylthio or phenyl groups. R may also be optionally substituted with a group having the configuration --O--CH.sub.2 A, where A is a phenyl or a naphthyl group. The phenyl group may be substituted with one or more halogen atoms, nitro groups, lower alkyl groups, or lower alkoxy groups.
Typical of the compounds disclosed in the Offenlegungsschrift is the compound of Structure 1: ##STR3##
Although the compounds disclosed within the Offenlegungsschrift are active herbicides, the need still exists for even better herbicides. Weeds are very damaging to important crops such as rice and wheat and they decrease crop yield. In the current world situation, wherein food shortages are acute, it is most important to harvest the maximum possible yields of crops such as rice or wheat. Thus, a need exists for a particularly effective herbicide which will destroy as many weeds as possible without causing significant damage to desired crops, e.g., rice and wheat.
According to the instant invention, compounds have been discovered which are highly active herbicides and yet cause minimal damage to certain desired crops, e.g., rice and wheat and especially the major world food crop, rice.
The preparation and fungicidal utility of 2-(4-chlorophenyl)-1,2,4,5,6,7-hexahydro-3H-indazol-3-one is disclosed in Takeda Chem. Ind. Paper, Chem. Abs., 67, 11542h (1967) ##STR4##
2-Aryl-4,5,6,7-tetrahydro-1-alkyl-1H-indazol-3(2H)-ones are claimed as antipyretics in Ger. 668.628 [assigned to P. Beierdorf & Co. AG, Chem. Abs., 33, 5131.sup.2 (1939)] and U.S.P. 2,104,348 [assigned to E. R. Squibb Co., Chem. Abs., 32, 1869.sup.1 (1938)]. ##STR5##
1-Phenyl-3,4-trimethylenepyrazolone is disclosed in U.S. Pat. No. 1,685,407 (1928) with utility as intermediate for making dyes and medicinal compounds. C. Mannich in Arch. Pharm. 267, 699-702 (1929) and in Brit. 260,577 describes the preparation of 1-phenyl-3,4-trimethylenepyrazolones. ##STR6##
R. P. Williams et al. in J. Med. Chem. 13, 773 (1970) reports the preparation and evaluation as antiinflammatory agents compounds of the following type: ##STR7## X = H, Br, F.